Sensing mechanism for accounting machines



March 23, 1954 A. SMITH SENSING MECHANISM FOR ACCOUNTING MACHINES 3 Sheets-Sheet 1 Filed Oct. 11, 1950 mum on Oh INVENTOR. GEORGE A. SMITH ATTORNEYS.

March 23, 1954 $M|TH 2,673,034

SENSING MECHANISM FOR ACCOUNTING MACHINES Filed 00TH 11, 1950 3 Sheets-Sheet 2 F G. 2. 14 12 54 a0 80 44 42 4o I II 9 27 34 a 2sp28 4H 7 if 6 F 0'0 L i I t; 2 l l I \UZ"H/72 i I mm, a E A a Ill-I l gz lso in:

56 '0 [T files I24 INVENTOR.

GEORGE A, SM/ TH F/G. 4. g 4 7 ATTORNEYS.

March 23, 1954 G. A. SMITH 2,673,034

SENSING MECHANISM FOR ACCOUNTING MACHINES Filed Oct. 11, 1950 5 Sheets-Sheet 5 I44 I46 I INVENTOR.

GEORGE A SMITH BY m W7 ATTORNEYS.

Patented Mar. 23, 1954 SENSING MECHANISM FOR ACCOUNTING MACHINES George A. Smith, Chestnut Hill, Pa., assignor to General Register Corporation, Long Island City, N. Y., a corporation of New York Application October 11, 1950, Serial No. 189,521

13 Claims. 1

This invention relates to sensing mechanism for accounting machines and has particular ref-- erence to means for sensing pips on slugs or holes in cards which are selectively arranged to carry information, the sensing means being arranged to provide for indication, printing, or calculation determined by such pips or holes.

Pips may be found in metallic slugs by distortion of the metal and when so formed are relatively fragile particularly when they are of small size and closely arranged .for the compact recording of information. Holes in cards are likewise subject to distortion in repeated use by reason of engagement with sensing elements. It is one object of the present invention to provide sensing means which may be used in conjunction with pips on slugs or holes in cards and which will avoid damage of the same.

A further object of the present invention is the provision of sensing means of high accuracy and capable of use where the indicating elements such as pips or holes are located in close lines for compactness.

A further object of the present invention is the provision of sensing means which involves positive operation without the use of springs for control of sensing movements.

These and other objects of the invention particularly relating to details of construction and operation will become apparent from the following description read in conjunction with the accompanying drawings, in which:

Figure l is a vertical section through portions of a ticket-issuing machine with which the improved sensing mechanism is associated for the sensing of pips on slugs;

Figure 2 is a horizontal section showing in detail certain of the elements at the upper portion of Figure 1;

Figure 3 is a verticalsection taken on the broken surface, the trace of which is indicated at '3-3 in Figure 1;

Figure 4 is a fragmentary elevation showing certain parts at the left-hand .side of Figure 1;

Figure 5 is a side elevation of one of the parts of the mechanism illustrated in Figure 1;

Figure 6 is an end elevation of the same part;

Figure 7 is a top plan view of a slug such as used in Figure 1;

Figure '8 is an elevation, partly insection, similar to Figure "1, but showing in particular sensing means suitable for sensing the holes in cards;

Figure 9 is a horizontal section showing certain parts at the upper portion of Figure '1, the section being taken onthe plane thetrace of which is indicated at 9-8 in 8; and

Figure 10 is .an exploded perspective view showing certain of the elements of the sensing mechanism.

Reference will now-be made to Figures 1 to 7, inclusive, showing the slug zpip asensing mechanism-which is-adapted for use'inrsucha machine as that illustrated and described in the application of Reuben H. Helsel, Serial Number 68,001, filed December 29, 1948. The mechanism of said application is particularly adapted for the issuance of transportation tickets which are printed by the machine .upon the insertion of metallic slugs which carry type faces for the imprinting of variable data on tickets. Said machine is adapted in particular to issue strips containing multiple tickets, the individual tickets of a strip, for example, providing for passages between pairs of railroad stations or other locations. As described in said application, the machine not only prints and issues tickets as aforesaid, but serves as an accounting mechanism keeping records in printed form of the issues of the tickets, the records including, for example, such matters as the particulars of the types of tickets issued and the fares charged, taxes thereon, etc. In addition, the mechanism provides a totalizer so that the aggregate amounts of fares and taxes may be determined from time to time. In order to accomplish these accounting ends, the slugs are provided with pips arranged in transverse lines and recording on each slug the information to be derived therefrom for recording purposes.

The present invention will be described in particular as applied to the machine of said Helsel application which will typify the uses of the invention. To this end there are shown in the drawings and described certain parts of said machine as are necessary to indicate the fashion in which the sensing means operates. For more complete details, reference may be had to said pending Helsel application.

A guideway provided .at .2 serves for the reception and guidance of longitudinal movement of the slug 4 which is particularly illustrated in Figure '7 and will be recognized to be the slug used in said Helsel machine. This slug carries various pips 6 projecting from its upper surface and selectively arranged in various lines across the slug so that the positions of these pips are indicative of information pertaining to the slug and the particular ticket or tickets to be issued thereby. Certain of the pips may not have numerical significance but may, for example, indicate various .classes of tickets or the identification of the stations between which the corresponding tickets are to'be used. Other assemblies of pips, however, have truly numerical significance in indicating, for example, fares charged for the tickets and taxes which may be assessed on the sales. While the pips of both classes control sensing mechanism to provide recording, the pips of the numerical classes may additionally control accumulating devices for the totaling of the fares and taxes. In order to simplify the description and at the same time render itmore general particular reference will be made to .both the v. re'cording :of the numerical values of one set of pips and to the totalizing of these values.

A shaft 8 is rotatable during the cycle of the machine and carries a pair of cams I and I2 I acting respectively on rollers I4 and I6 carried by bell cranks I8 and which are connected through their hubs to a transverse shaft 22. The ends of the bell cranks opposite the rollers are connected by a pin 24 to which are pivoted links 26 and 28 in turn pivoted at 21 and 29 to levers 30 and 32 which are secured to a rock shaft 34. The levers 30 and 32 are connected by a transverse pin 36 and have pivoted to them'links 38 and 40 at 42 and 44, respectively. These links are connected by a pin 46 which is arranged to slide in slots 48 and 50 provided in vertical plates 52 and 54. Journalled on the pin 46 are sensing members 56 which at their forward ends are provided with sharp upwardly directed noses 58 and which are provided near the pin 46 with downwardly extending projections 60 having sloping rear edges arranged to ride up a pin 62 carried by the plates 52 and 54. The sensing members 58 are urged downwardly by light leaves of a spring comb 64 which is carried by a transverse bar secured to a guide member 60 provided with slots 66, best illustrated in Figures 5 and 6, which serve for the longitudinal guidance of the sensing members 56. The lower front end of each sensing member 56 is bevelled, as indicated at 10, so that during its forward movement it may readily ride up and over a pip 6 which is in alignment with its path. It may be here explained that the machine, as shown in said Helsel application, is provided with means for accurately fixing the slug positions at the time of sensing so as to bring a predetermined transverse line of the slug into the path of each sensing element.

Arranged to slide in each slot 66 above a sensing element is a corresponding slide I2, these slides being lightly held downwardly by the action of the leaves 14 of a spring. comb mounted on the member 68. Each of the slides 12 is provided at its lower edge with teeth 16 which are respectively arranged to correspond to the various pip positions transverse of the slug. As will be hereafter described more fully, a sensing element will' normally move forwardly in a position to miss the teeth I6 but upon engagement with a pip will be raised so as to engage selectively one of the teeth, thereafter carrying forwardly with it during its stroke the slide 12.

Links are connected to the slide 12 at pivots l8 and are, in turn, connected at 82 to members 84 which are loosely journalled on the shaft 34. The members 84 are provided with type faces indicated at 86 which correspond in their positions and designations to the pip positions transverse of the slugs. The members 84 are provided with shoulders 88 which, as will appear hereafter, cooperate with the pin 36. The members 84 are also provided with shoulders 90 which serve to limit their clockwise rotations, as viewed in Figure 1, by engagement with a fixed pin 92. The members 84 are provided with teeth 94 which are in mesh with teeth 96 on corresponding sectors 68 pivoted on a transverse pin I00. Corresponding to each sector is a second sector I 02, also pivoted on pin I00, and urged in a counterclockwise direction with respect to sector 98 by an individual spring I04 to a point limited by engagement of pin I06 carried by sector 98 with the lower end of a slot I08 formed in sector I02. When the parts are in rest position, however, the sector I02 has its counterclockwise movement .limitedby .en-

4 gagement with a fixed pin I03, so that pin I06 is in the upper end of slot I08.

The teeth IIO of sector I02 are arranged to mesh at proper times with the teeth of the corresponding pinion II2 which forms part of an accumulator assembly carried by plates H4 and pivoted to rock about a pin I I6, the rocking movement being imparted to the accumulator assembly by the action of suitable cams on shaft 8 on rollers H8 and I20 carried by the assembly. The accumulator assembly includes number printing wheels I22.

Reference to the Helsel application mentioned above will show that the members 84, sectors 88 and I02, and the accumulator assembly illustrated herein correspond to what is shown and described in said application, and since the operation from the standpoint of printing and accumulating is the same as in said application, it will not be more fully described herein.

There is, however, one addition to the accumulator assembly in the nature of a pair of cam extensions I24 carried by the plates I i4 and adapted to act as the accumulator assembly moves to the right in Figure 1 upon rollers I26 carried by a slide I28 which is urged downwardly by springs I30. As will be clear from Figures 1 and 4, the slide I 28 has a flat upper surface over which there is adapted to project the slides 12 which, in turn, will be raised by the slide I28 when the accumulator mechanism is rocked to the right or rearwardly.

Printing by the type members 86 is effected as described in detail in said Helsel application by the arrangement of a hammer assembly I34 which carries a suitable hammer I32 tripped at the proper time to force a record strip and carbon paper into contact with the type. The printing arrangement associated with the accumulator numeral wheels I22 is as described in said Helsel application and is not shown herein.

Definite positioning of the members 84 is accomplished as in said Helsel application by engagement of the end I3I of a member pivoted to a fixed pin at I33 between the teeth 94, this member being operated through arm I35 from a suitable cam on the shaft 8.

The operation of the mechanism so far described is as follows:

The elements in their rest positions are as illustrated in Figure 1. When the sensing operation is about to begin, rotation of the shaft 8 takes place causing the bell cranks I8 and 20 to rock clockwise as viewed in Figure l. The result is to rock the members 30 and 32 counterclockwise causing the sensing members 56 to move toward the left or forwardly as viewed in Figure 1. As the sensing members move forwardly, their projections 60 are released by the pin 62 and their forward ends are lightly pressed downwardly by the spring leaves at 64. Forward motion occurs at a level such that the nose 58 of each sensing member clears teeth 16 of the corresponding slide until the bevel 10 engages a pip 6 in its path by which pip it is vcammed upwardly to engage a corresponding tooth of the slide 12. As the forward motion then continues, the slide 12 is correspondingly moved forwardly by the sensing member which continues to ride over the top of the pip. As the slide 12 moves forwardly it carries with it the corresponding member 84 and at the end of the stroke of the sensing member 56, the member 84 will have been displaced to aposition corresponding tothe position of the pip, thereby locating a corresponding type .element 86 in line with the hammer I32. As will be evident from the construction, the sensing members 56 have an invariable extent of movement, and the movement of each slide I2. and member 84 corresponds to that amount of the full stroke which follows engagement of a pip by the corresponding sensing member. At the completion of the full forward stroke of the sensing members, the member I3I is engaged between teeth 94 looking the members 84 in definite positions, the member I3I being so shaped as to have a wedge-like action between the teeth, thus insuring positive and accurate alignment. The printing operation is then effected by the tripping of the cooked hammer I32. It will be noted that the shock involved in the printing is not taken by the sensing member but rather by the element I3I which is positioning the members 84.

In the meanwhile, each sector 98 will have been rotated clockwise to an extent corresponding to the rotation of its corresponding member 84, and the sector I02 will also have been rotated following the engagement of the lower end of the slot I65 by pin I06, the operation occurring as described in said Helsel application. The member I3! is now freed from the members 84 and they are consequently free to be restored to initial position. Just prior to the beginning of their restoration, the accumulator assembly is rocked toward the right in Figure 1 producing meshing of the pinions II2 with the teeth IIO of the sectors I02. As this rocking action takes place, the cams I24 act on rollers I25 to raise slide I28 and this, in turn, raises all of the slides I2 out of engagement with the points 56 of the sensing members 56. The result of this is that the sensing members are free to move on their return strokes clearing the teeth I5. As

the clockwise oscillation of the members 30 and in which their shoulders 90 engage pin 92. Dur- 1 ing these return movements of the members 84, the accumulator pinions II2 will be rotated to extents corresponding to the initial displacements of the members 84 thus serving to operate the accumulator mechanism as described in said Helsel application. At the end of the operation, the sensing members 56 will have been restored to their original positions and this will also be true of the slides I2. The numeral wheels I 22 of the accumulator will accordingly be advanced to add to their original indications the amounts determined by the pips on the slugs.

It may be here noted that while only three members 84 are illustrated, there may be various other groups of these members all of which may be similarly controlled by devices such as those described including pairs of members 36 and 32 secured to the shaft 34.

From the above description, it will be evident that the pips 6 on the slug are relieved from the application of any substantial forces which might tend to distort or wear them. They serve solely for raising the sensing members 56 into engagement with teeth I6 and during the advance of the slides I2 they merely hold and maintain that engagement. In fact, if the teeth I6 are undercut and the noses 58 of sensing members 56 correspondingly project forwardly, the

sensing members 56 may be raised out of contactv with the pips 6 during the forward strokes of the slides I2. The pips 6 are not even caused to assume the pressure of leaves 58 during return of the slides I2 due to the action of slide I28 which disengages teeth 16 from the points 58 of the sensing members. It may be further noted that the movements imparted to the members 84 are positive in both directions, there being no springs involved in either motion. There will now be described the operation of a card sensing mechanism illustrated particularly in Figures 8 to 10, inclusive, which is in many respects similar to the sensing mechanism already described so that those parts which are duplicated need not be described in detail, the constructions and functions being as previously pointed out.

Rocking members I35 corresponding to members 30 and 32 are provided and these are connected by links I38 to a transverse pin I40 which is guided for movements in slots I42 in plates I44. J ournalled on the pin I40 are sensing members I46 which are provided with noses I48 projecting downwardly and adapted to slide over the surface of a card I52 provided with elongated openings I and positioned by a guide arrangement shown at I54. Arrangements (not shown) provide for alignment of the cards in a lengthwise direction so that their openings I50 are lined up with the paths of movement of the sensmembers I 46 which are guided in slots I62 in a member I64. Also guided in these slots are members Its which are provided teeth I58 engageable by single teeth I56 on the sensing members I46. Each of the members I60 is pivoted to a link I85 which is in turn pivoted to a member I 58 corresponding to a member 84 previously described and carrying type elements indicated at I'I0. Each member I68 is provided with a shoulder I'I2 engageable by a transverse pin I14 carried by members I36. Each member I68 is also provided with a shoulder I16 engageable with a fixed stop pin I78. Each member I68 is provided with teeth I corresponding to teeth 54 previously described and these teeth are arranged to be engaged by a member I82 corresponding to I3I. For simplicity, the sectors intermediate the members I68 and the accumulating mechanism I84 are omitted, the accumulating mechanism being provided in a frame pivoted at I86 as previously described.

Each member I60 is provided with a sloping lower edge portion I88 which is arranged to ride over a fixed pin I90. When the parts are in rest position, each link I66 rests on a pin I61 carried by its corresponding member I66 to insure proper position of member I60 as illustrated.

Each of the sensing members I46 is provided with an opening having a sloping portion I92 and a socket I84 which, when the sensing members are in rest position, lies over the fixed pin I96. The sensing members are urged downwardly by the leaves I96 of a spring member secured to I64.

The operation of the card sensing mechanism may now be described. Assuming that a card is in proper position, counterclockwise rotation of the plates I36 will advance the sensing members which will first clear their sockets I94 from pin I96 and will thereafter drop as the sloping edge I92 rides over pin I96. Each sensing member will then ride over the surface of the card under the light force applied by its corresponding spring leaf I98. When a nose I48 reaches the position of a hole I50 it will drop therein bringingits tooth I56 into engagement with a tooth- I58 of the corresponding member I60, the tooth which is engaged being that corresponding to the position of the hole I50. Prior to reaching a hole, the nose I48 will be so raised by the surface of the card that the tooth I56 will clear teeth I58.

As soon as engagement of the teeth occurs, the corresponding member I60 will be advanced and, immediately upon such advance, will be rocked upwardly by the edge I88 which rides over pin I90. This action serves additionally to raise the sensing member I46 so that its nose I48 will be raised clear of the upper surface of the card. The holes I50 are elongated in the direction of motion of the sensing members so that their edges are not engaged by the nose during the forward movement after it first enters the hole. As the forward movement continues the members I58 will be rocked to a final position, at the end of the stroke of the sensing members, such that their displacement will correspond to the position of the corresponding hole in the card. At theend of the forward movements, locking of the members I68 by member I82 will occur and printing may be effected.

On the reverse stroke the sensing members I46 will move relatively to the members I60 and in this movement the tooth I56 will click over the teeth I58. It will be noted, however, that this action is without any engagement of the noses I48 with the cards and, consequently, the cards are not subject to damage. The various members I68 will be successively picked up by the pin 1'" to be returned to their initial positions and in such return the accumulator will be actuated as previously described. At the end of the return movement, the parts will have returned to the initial positions illustrated in Figure 8. It will be noted that in this modification of the invention, as in the case of the pip sensing mechanism, there is no force exerted such as will serve to damage the indicating means on the element being sensed. There is also as in the previous modification a positive movement imparted in both directions to the type-carrying members I68.

What is claimed is:

1. A sensing device for selectively positioning an element under the control of indicia located in a stationary record member to be sensed comprising a sensing member, means for moving said sensing member across the stationary record member and an indicia thereon, said sensing member being movable transversely to the first mentioned movement upon sensing said indicia, and a member associated with said sensing member and constructed and arranged to be picked up by said sensing member upon said transverse movement of the sensing member and thereupon to be moved by said sensing member during a remaining portion of the movement of said sensing member across the record member.

2. A sensing device for selectively positioning an element under the control of indicia located on a stationary record member to be sensed comprising a sensing member, means for moving said sensing member across the stationary record member and an indicia thereon in a stroke of invariable length, said sensing member being movable transversely to the first mentioned movement upon sensing said indicia, and a member associated with said sensing member and constructed and arranged to be picked up by said sensing member upon said transverse movement ofthe sensing member and thereupon to be moved by said sensing member during the remaining portion of the movement of said sensing member across the record member.

3. A sensing device for selectively positioning an element under the control of indicia located on a stationary record member to be sensed comprising a sensing member, means for moving said sensing member across the stationary record member and an indicia thereon, said sensing member being movable transversely to the first mentioned movement upon sensing said indicia, and a member associated with said sensing member and constructed and arranged to be picked up by said sensing member upon said transverse movement of the sensing member and thereupon to be moved by said sensing member during a remaining portion of the movement of said sensing member across the record member, said sensing member having a tooth and the last mentioned member having a plurality of teeth selectively engageable by said tooth in accordance with the indicia sensed.

4. A sensing device for selectively positioning an element under the control of indicia located on a stationary record member to be sensed comprising a sensing member, means for moving said sensing member across the stationary record member and an indicia thereon in a stroke of invariable length, said sensing member being movable transversely to the first mentioned movement upon sensing said indicia, and a member associated with said sensing member and constructed and arranged to be picked up by said sensing member upon said transverse movement of the sensing member and thereupon to be moved by said sensing member during the remaining portion of the movement of said sensing member across the record member, said sensing member having a tooth and the last mentioned member having a plurality of teeth selectively engageable by said tooth in accordance with the indicia sensed.

5. A sensing device for selectively positioning an element under the control of indicia located on a stationary record member to be sensed comprising a sensing member, means for moving said sensing member across the stationary record member and an indicia thereon, said sensing member being movable transversely to the first mentioned movement upon sensing said indicia, and a member associated with said sensing memer and constructed and arranged to be picked up by said sensing member upon said transverse movement of the sensing member and thereupon to be moved by said sensing member during a remaining portion of the movement of said sensing member across the record member, said sensing member having a return stroke during which it moves relatively to the last mentioned member, and the last mentioned member having a return movement lagging that of said sensing member.

6. In combination with an element to be selectively positioned under the control of indicia located on a stationary record member to be sensed, a sensing member, means for moving said sensing member across the stationary record member and an indicia thereon, said sensing member being movable transversely to the first mentioned movement upon sensing said indicia, a member as sociated with said sensing member, connected to said element, and constructed and arranged to be picked up by said sensing member upon said transverse movement of the sensing member and thereupon to be moved by said sensing member during a remaining portion of the movement of said sensing member across the record member to advance said element, and means for positively imparting a return movement to said element 7. In combination with an element to eel-sc tively positioned under the control of indicia located on a stationary record member to be sensed, a sensing member, means for positively moving said sensing member across the stationary record member and an indicia thereon, said sensing member being movable transversely to the first mentioned movement upon sensing said indicia, a member associated with said sensing member,

connected to said element, and constructed and arranged to be picked up by said sensing member upon said transverse movement of the sensing member and thereupon to be moved by said sensing member during a remaining portion of the movement of said sensing member across the record member to advance said element, and means for positively imparting a return movement to said element.

8. In combination with an element to be selectively positioned under the control of indicia located on a stationary record member to be sensed, a sensing member, means for moving said sensing member across the stationary record member and an indicia thereon in a stroke of invariable length, said sensing member being movable transversely to the first mentioned movement upon sensing said indicia, a member associated with said sensing member, connected to said element, and constructed and arranged to be picked up by said sensing member upon said transverse movement of the sensing member and thereupon to be moved by said sensing member during the remaining portion of the movement of said sensing member across the record member to advance said ele ment, and means for positively imparting a return movement to said element.

9. In combination with an element to be selectively positioned under the control of indicia located on a stationary record member to be sensed, a sensing member, means for positively moving said sensing member" across the stationary record member and an indicia thereon in a stroke of invariable length, said sensing member being movable transversely to the first mentioned movement upon sensing said indicia, a member associated with said sensing member, connected to said element, and constructed and arranged to be picked up by said sensing member upon said transverse movement of the sensing member and thereupon to be moved by said sensing member during the remaining portion of the movement of said sensing member across the record member to advance said element, and means for positively imparting a return movement to said element.

10. In combination with an element to be selectively positioned under the control of indicia located on a stationary record member to be sensed, a sensing member, means for moving said sensing member across the stationary record member and an indicia thereon, said sensing member being movable transversely to the first mentioned movement upon sensing said indicia, a member associated with said sensing member, connected to said element, and constructed and arranged to be picked up by said sensing member upon said transverse movement of the sensing member and thereupon to be moved by said sensing member during a remaining portion of the movement of said sensing member across the record member to advance said element, and means for positively imparting a, return movement to said element, said sensing member having a tooth and the last mentioned member having a plurality of teeth selectively engageable by said tooth in accordance with the indicia sensed.

11. In combination with an element to be selectively positioned under the control of indicia located on a stationary record member to be sensed, a sensing member, means for positively moving said sensing member across the stationary record member and an indicia thereon, said sensing member being movable transversely to the first mentioned movement upon sensing said indicia, a member associated with said sensing member, connected to said element, and constructed and arranged to be picked up by said sensing member upon said transverse movement of the sensing member and thereupon to be moved by said sensing member during a remaining portion of the movement of said sensin member across the record member to advance said element, and means for positively imparting a return movement to said element, said sensing member having a tooth and the last mentioned member having a plurality of teeth selectively engageable by said tooth in accordance with the indicia sensed.

12. A sensing device for selectively positioning an element under the control of indicia located on a record member to be sensed comprising a sensing member, means for moving said sensing member across the record member and an indicia thereon, said sensing member being movable transversely to the first mentioned movement upon sensing said indicia, a member associated with said sensing member and constructed and arranged to be picked up by said sensing member upon said transverse movement of the sensing member and thereupon to be moved by said sensing member during a remaining portion of the movement of said sensing member, and means moving said sensing member out of engagement with said record member after said transverse movement of the sensing member for a remaining portion of the movement of said sensing member across the record member.

13. In combination with an element to be selectively positioned under the control of indicia located on a record member to be sensed, a sensing member, means for moving said sensing member across the record member and an indicia thereon, said sensing member being movable transversely to the first mentioned movement upon sensing said indicia, a member associated with said sensing member, connected to said element, and constructed and arranged to be picked up by said sensing member upon said transverse movement of the sensing member and thereupon to be moved by said sensing member during a remaining portion of the movement of said sensing member to advance said element, and means moving said sensing member out of engagement with said record member after said transverse movement of the sensing member for a remaining portion of the movement of said sensing member across the record member, and means for positively imparting a return movement to said element.

GEORGE A. SMITH.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,340,581 Cooper Feb. 1, 1944 2,508,603 Gollwitzer May 23, 1950 

